Reassessment of cancer predisposition of Fanconi anemia heterozygotes.

The hypothesis that heterozygotes for the Fanconi anemia (FA) gene are predisposed to cancer was investigated by comparing the observed and expected numbers of cancer cases and deaths in 25 extended families of FA probands. This study demonstrated no overall excess of cancers of cancer deaths for any age or sex category of blood relatives and no unusual number of cancers among the obligate heterozygotes. Deaths from leukemia among blood relatives were fewer than expected. For bladder, stomach, and breast cancer there were more deaths and cases among blood relatives than expected, although the differences were not statistically significant. An excess of deaths at an early age from lung and stomach cancer was noted among the FA blood relatives. Among spouse controls there were fewer deaths than expected from bladder, stomach, and breast cancer; thus the expected numbers may be inappropriately high for this sample. Therefore, the question of predisposition to bladder, stomach, and breast cancer among FA heterozygotes remains unresolved.